One such contact frame constitutes the subject matter of French patent No. 2 623 313 (see also U.S. Pat. No. 4 900 272).
According to that patent, the contact frame includes, in particular, card guide means and contact elements which provide electrical connections with conducting tabs on the I.C. card and via which circuits are established for the benefit of the apparatus including the I.C card reader.
Such a frame essentially comprises a piece made of molded insulating plastic supporting the contact elements which are installed in connection windows by being embedded in the bars of the frame. The frame supports two series of contact elements disposed facing each other. Towards the middle of the frame, these elements are shaped to project beneath the plane surface of the frame. It is these shaped portions that rest against the electronic component of the I.C card and consequently establish contact.
At either side of the frame, the contact elements project outwards from the window bars in which they are embedded to form connection pins for connection to a printed circuit board.
In general, such a frame is associated with a cover which is installed beneath the frame, the cover and the frame forming a housing into which the I.C card is inserted.
This frame and cover assembly is generally mounted beneath the printed circuit board. The shaped portions of the connection elements therefore extend downwards and the contact elements at their ends forming connection pins are folded upwards to be soldered to the printed circuit board.
If the term "front" is used for that side of the frame which is closest to the I.C card insertion slot and the term "rear" for the opposite side of the frame, then one series of connection pins is at the front of the frame and the other series is at the rear of the frame. Outside the molded insulating material, between leaving the bar of the frame and being connected in or on the printed circuit board, each bare pin therefore forms a bend.
Such an arrangement poses several problems.
Since the printed circuit board is on top above the contact frame, the insertion slot through the housing of the apparatus must be at a distance from the top lid of the housing, which distance is defined by the room taken up by the printed circuit board which may possibly have bulky components on its top surface. Unfortunately, it is preferably to leave room inside the housing beneath the I.C card connector, and for ergonomic reasons to place the insertion slot as high as possible relative to the housing of the apparatus in order to facilitate handling by the user.
In addition, the printed circuit board may need to be connected to a device situated beneath the I.C card connector, which device may be constituted by a keyboard, for example. The presence of the I.C card connector beneath the printed circuit board does not facilitate making such a connection, if required.
In addition, as mentioned above, the prior art arrangement has bent portions of the connection pins which are bare at the front of the frame close to the insertion slot. Having these bent portions at the front presents several problems.
When I.C cards are electrostatically charged, discharges may take place, given the short distance between the I.C card and the bent portions of the front connection pins. Thus, static electricity may give rise to errors or damage in the reader system.
In addition, the bent portions of the connection pins are close to the insertion slot for the I.C card, and it is relatively easy to damage these connection pins by means of a tool such as a screwdriver blade or the like, and this arrangement is thus relatively fragile if such acts of vandalism are performed.
Further, it is also possible to connect wires to these portions of the connection pins close to the insertion slot, thus making it possible to simulate the circuits of the I.C card and thus use the apparatus fraudulently.
The present invention seeks to solve these problems by providing a contact frame arrangement for the reader of an I.C card that enables the printed circuit board to be installed beneath the contact frame and cover assembly, while still enabling the I.C card to be inserted conventionally, i.e. with its contact zone facing upwards.
European patent document EP-O 213 041 filed Aug. 8, 1986 discloses a contact frame in which the ends of the blades that form connection pins terminate on one side of the frame opposite to their contact ends. These blades are embedded in plates which engage on studs carried by the support frame and they are locked in place by forming heads on these studs, with the plates in the two sets of blades being superposed.
That frame suffers from numerous technical problems which, in particular, make it particularly expensive to implement.
To make such a frame, a large number of pieces need to be assembled, and these pieces are all very small, making them difficult to manufacture and to assemble.
An I.C card must be positioned very accurately relative to the contact ends in order to obtain a proper force exerted on the conducting tabs of the I.C card so as to avoid problems of contact resistance or problems of wear on the contact elements and on the cards. Given the that the plates are stacked on the prior frame, tolerances are added together and this means that very tight tolerances are required on each of the stacked-together pieces.
In addition, to manufacture that frame, it is necessary to provide two different types of blade, to perform two overmolding operations, and to perform meticulous assembly with the support frame, which itself must also be shaped.
Finally, the space occupied in the thickness direction by such a contact frame is particularly large. However, it is desirable of an I.C card reader to be as compact as possible, for example in order to make portable apparatuses.